[FFmpeg-devel] [PATCH 3/3] lavf/utils: add flag to fill unset timestamps from wallclock offset

[Rodger Combs]

---
 libavformat/avformat.h      |  1 +
 libavformat/internal.h      |  5 +++++
 libavformat/options_table.h |  1 +
 libavformat/utils.c         | 12 ++++++++++++
 4 files changed, 19 insertions(+)

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index d10d583dff..a039a2764d 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1451,6 +1451,7 @@ typedef struct AVFormatContext {
 #define AVFMT_FLAG_SHORTEST   0x100000 ///< Stop muxing when the shortest stream stops.
 #define AVFMT_FLAG_AUTO_BSF   0x200000 ///< Add bitstream filters as requested by the muxer
 #define AVFMT_FLAG_DISCARD_CORRUPT_TS 0x400000 ///< Discard timestamps of frames marked corrupt
+#define AVFMT_FLAG_FILL_WALLCLOCK_DTS 0x800000 ///< Fill missing or discarded DTS values from wallclock (for live streams)
 
     /**
      * Maximum size of the data read from input for determining
diff --git a/libavformat/internal.h b/libavformat/internal.h
index 36a57214ce..3abf1dc720 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -192,6 +192,11 @@ struct AVStreamInternal {
     int need_context_update;
 
     FFFrac *priv_pts;
+
+    /**
+     * The wallclock timestamp of the most recent read packet (if AVFMT_FLAG_FILL_WALLCLOCK_DTS is set)
+     */
+    int64_t cur_wallclock_time;
 };
 
 #ifdef __GNUC__
diff --git a/libavformat/options_table.h b/libavformat/options_table.h
index 515574d3e0..64febc7a21 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -59,6 +59,7 @@ static const AVOption avformat_options[] = {
 {"shortest", "stop muxing with the shortest stream", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_SHORTEST }, 0, 0, E, "fflags" },
 {"autobsf", "add needed bsfs automatically", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_AUTO_BSF }, 0, 0, E, "fflags" },
 {"discardcorruptts", "discard timestamps on corrupted frames", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_DISCARD_CORRUPT_TS }, 0, 0, E, "fflags" },
+{"fillwallclockdts", "fill missing or discarded DTS values from wallclock (for live streams)", 0, AV_OPT_TYPE_CONST, { .i64 = AVFMT_FLAG_FILL_WALLCLOCK_DTS }, 0, 0, E, "fflags" },
 {"analyzeduration", "specify how many microseconds are analyzed to probe the input", OFFSET(max_analyze_duration), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, D},
 {"cryptokey", "decryption key", OFFSET(key), AV_OPT_TYPE_BINARY, {.dbl = 0}, 0, 0, D},
 {"indexmem", "max memory used for timestamp index (per stream)", OFFSET(max_index_size), AV_OPT_TYPE_INT, {.i64 = 1<<20 }, 0, INT_MAX, D},
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 98af941e9f..22cefb2975 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -881,6 +881,18 @@ int ff_read_packet(AVFormatContext *s, AVPacket *pkt)
                    pkt->stream_index);
         }
 
+        if (s->flags & AVFMT_FLAG_FILL_WALLCLOCK_DTS) {
+            int64_t cur_wallclock_time = av_gettime_relative();
+            if (pkt->dts == AV_NOPTS_VALUE && st->cur_dts != AV_NOPTS_VALUE && st->internal->cur_wallclock_time) {
+                int64_t wallclock_offset = av_rescale_q(st->internal->cur_wallclock_time - cur_wallclock_time, AV_TIME_BASE_Q, st->time_base);
+                pkt->dts = st->cur_dts + FFMAX(wallclock_offset, 1);
+                av_log(s, AV_LOG_VERBOSE,
+                       "Filled timestamp from wallclock (stream = %d; last = %"PRId64"; val = %"PRId64")\n",
+                       pkt->stream_index, st->cur_dts, pkt->dts);
+            }
+            st->internal->cur_wallclock_time = cur_wallclock_time;
+        }
+
         pkt->dts = wrap_timestamp(st, pkt->dts);
         pkt->pts = wrap_timestamp(st, pkt->pts);
 
-- 
2.14.3